"Advancing the future of wireless communications"


The Federal Communications Commission (FCC) recently allocated three 100 MHz bands of radio spectrum for the Unlicensed National Information Infrastructure (U-NII), with only minimal controls on radio emissions in. Moreover, the FCC report and order explicitly states "...we are not adopting a channeling plan, spectrum modulation efficiency requirement or a spectrum etiquette as we believe such technical standards are unnecessary at this time, could preclude certain technologies, and could unnecessarily delay implementation of U-NII devices." The U-NII is designed to attract a large number of smaller diverse vendors and service providers and rapidly bring into existence a great variety of novel wireless systems and services. This is in contrast to auctions of licensed spectrum which resulted in expensive acquisition of bandwidth by large telecommunications companies. It is hoped that competition among U-NII services will result in substantial economic and social benefits on a national scale. For example, inexpensive, short-range, high-speed (>10Mb/s) wireless data communications will help realize the goal of connecting all homes and schools to advanced telecommunications services -- as stated in the Telecommunications Act of 1996.

The U-NII scenario offers a unique set of technical challenges not experienced in other wireless communications systems where access is controlled by the license holder. Consider that in a licensed system, access to radio channels is regulated so that a user faces only controlled interference from other users of that system. Unlicensed band systems are fundamentally different. Each autonomous system can use distinct modulation schemes and multiaccess methods and carry traffic characteristic of its market niche. Most importantly, however, each autonomous system can compete independently for resources paying no attention to interference it creates in other nearby systems, and can suffer from interference created by others, without being able to communicate directly and coordinate its activity with nearby systems.

Since almost all research on quality of service (QoS) in wireless systems has been focused on systems such as cellular that operate in licensed bands and carry a specific class of traffic, our present understanding of mutually interfering autonomous systems is at best sketchy. Add to this the fact that systems providing service to different traffic classes or using different multiaccess methods will generate interference with different temporal and spectral characteristics and a strong need for fundamental studies are apparent.

We therefore seek to develop a general understanding of autonomous mutually interfering systems which will aid in the development of the U-NII. We also seek to understand the economics which will drive the envisioned U-NII "ecosystem". Our goal is to provide recommendations for robust modulation, access, adaptation strategies and general service types which are consonant with peaceful coexistence of U-NII service providers -- without being overly restrictive and winnowing the diversity of possible offerings. A step toward this goal is establishing a dialog among technologists, economists and service providers interested in the U-NII. The 1998 WINLAB Focus on U-NII is our envisioned forum for such exchange.